Speedometer



June 22 1926.

J. T: SIBLEY SPEEDOMETER Filed Feb. 5, 1924 Patented June 22, 1926.

UNITED STATES JAMES T. SIBLEY, QF NEW YORK, N. Y.

SPEEDOMETER.

Application filed February 5, 1924.

In my prior patent application, Ser. No. 663,579, filed September 19, 1923, l have shown a form of speedometer wherein the power for operating both speed'index and mileage train comes from a succession of airjet impulses, operating in the one case upon a disk or drum as a sort of turbine, and in the other through a closed chamber having a flexible wall, the movements of which are communicated through an escapement to the mileage number wheel train. Specific forms of disks and drums are shown and ydescribed which are designed with special reference to the calibration of the speed index.

The present improvement relates to changes in the means for such calibration, and is designed to simplify the same and render it more accurate. In general, the main structure of the speedometer is the same as that described in said prior application, the specic improvement residing in the provision of a sort of escape valve for the increased pressures at the higher or greater speeds. 1t has been found in actual practice that as the speed of the pump mo-v tor increases, the jet impulses become increasingly stronger to an extent not in exactproportion to the increase in speed. This makes it necessary to permit a portion of the excess pressure to escape, and utilize only a sufficient part thereof to effect accurate speed measurement.

In the accompanying drawing, it is not deemed necessary to illustrate the pump motor, the drawing being confined to the mechanism within the speedometer case, since the operation of the motor in producing jet impulses is fully set forth in the prior application.

In the drawing;

Fig. 1 is a vertical sectional view of the device taken on line I-I of Fig. 2.

Fig. 2 is a front view of the speedometer mechanism, the cover being removed to expose all parts of the same.

Fig. 3 is a top plan view, with the cover in section.

Fig. 4 is a similar bottom plan view.

Fig. 5 is a fractional plan view of the air valve. l

Figs. 6 and 7 are similar to Fig. 5, but showing different positions of the air vent.

The case ofthe speedometer consists of a back plate 1, upon `which a cover 2 is mounted, the cover having a glass 3 and a plate 4, with windows 5, located to expose Serial No. 690,712.

the trip and distance mileage trains 6 and 7, respectively, and also a sufficient portion of a speed index drum as further on described, all as is usual in devices of the kind.

The operative mechanism is all mounted upon the back plate 1, and consists of an airchamber 8, with its flexible wall 9, to which an escapement 10 is connected. An escapement wheel 11 is mounted upon a spindle 12, carried in bearings in brackets 13, 14. The spindle 12 has a worm 15 which meshes with the worm wheel 16 and drives the trip and distance mileage trains 6 and 7.

Supported in bearings in brackets 17 and 17 is a speed index shaft 18, the rotation of which is controlled by a spring 19 in the usual manner. Mounted upon the shaft 18 is anv open index drum 2() which has a single supporting arm 21, secured to the shaft. The drum is only a simple ring of sheet metal, entirely open so that the parts of the air duct may be located therein, and the 'drum may rotate without obstruction.

From air chamber 8 the air duct 22, being formed in the back plate 1 and cast integral with the bracket 13, leads to an upwardly extending outlet 23, terminating in a broad llat table 24, with a narrow slot 25 therein, and the upper face of the table is substantially upon a level with the upper edge of the drum 20.

Mounted upon the shaft 18 is a valve plate 26, made of thin sheet metal with its outer edge in the form of an involute, and nor-v mally carried upon the shaft 18 so that when the drum 20 has its index at 0, the longer diameter of the valve plate will completely cover the slot 25. From the side of the outlet 23, extends a nozzle 27 with its outer end flattened and terminating tangentially in close proximity to the inner face of the index drum 20.

t should be noted that while the valve plate 26 swings over and covers the slot 25, it does not actually touch the table 24, but is close enough to obstruct the free outflow of air from the slot 25. As the shaft 18 rotates the valve plate turns with it and because of the involute form of its profile, the outer end of the slot is gradually uncovered to permit a gradually increased outflow of air therefrom permitting uniform spacing of the graduations on the drum.

ln operation, it is understood that the jet impulses of air from a motor pump enter the chamber 8 through a connecting nipple 28, Where such jet impulses serve to vibrate the flexible chamber wall 9 and so operate the trip and distance mileage trains 6 and 7. These jet impulses also extend from the chamber 8, through the air duct 22' into the outlet end 23 and out through the nozzle 2T Where they impinge upon the inner face of the index drum 20, causing said drum and the shaft 18 to turn against the tension of the control spring 19, and the valve plate 2G at the same time will gradually uncover the slot 25, to permita gradually increased out flow of air through the slot.

The vibrations of the exible Wall 9 are in unison with those of the motor pump, so that the rotation of the trip and distance trains 6 and 7 is determined by the ratio of the Worm 15 and Wheel 16. But it is found that as the speed of the jet impulses increases, their action upon the drum 2O is not exactly uniform; that the more rapid they become the greater the pressure Within the air duct is' built up, so that for higher speeds the drum 2O will swing through a greater arc. Therefore to make the swing of the drum uniform it becomes necessary to correspondingly vent the air duct.

The exact form of the outline of the valvel plate 2G has been determined, after a long series of experiments, to be an involute of substantially the contour shown. Vhe-n calibrating, minor variations from the true swing' of the drum are corrected by slightly ending the disk toward or away from the face of the table 24, so as to vary the amount of the outlet from the slot 25. The direction of the slot 25 may be varied from a radial line With the shaft 18; as, for exam-A ple, it may be fat an angle as shown in Fig. 6 or in Fig. 7. The mounting of the valve plate upon the shaft- 18, includes a. friction hub 26 which enables it to be properly ad just'ed cir :uinferentially about the shaft, so as to bring-'it in proper relation to the index scale Which is on the face of the drum.

It is not thought necessary to illustrate all of the details of the speedometer, since the invention of the present case is confined to the .means for venting the air duct, so as to quickly, conveniently and accurately calibrate the instrument. It is to be understood that the same character of motor pump as is shown in my above named appli- Les spring for restraining the rotation of said drum, means for directing a. rapidly pulsating air jet within and against the inner face of said drum to rotate the same against the restraint of said control spring, and automatic means actuated in unison With said drum for gradually reducing the effect of said jet impulses.

2. In a speedometer, the combination of a pivotally mounted index member, a control spring connected to said member, means for directing a diagonally impinging pulsating air jet against an element of said member.l and means co-operative with saidv member varying the effect of the jet impulses in direct proportion to the movement of said member.

In a speedometer, the combination of a pivotally mounted shaft, an index drum concentrically mounted upon said shaft, said drum being open` at both ends, a control spring for said drum, an air jet nozzle di rected against the inner face of said drum, said nozzle being connected with an air suppl'y source, a lateral opening in the connections leading to said nozzle, anda valve disk mounted upon said shaft to gradually uncover said opening upon the rotation of said shaft and drum.

d. In a speedometer, the combination of a pivotally mounted index drum, av control spring therefor, means for directing a rapidly pulsating air jet against 4an inner part of said drum to rotate the saine against the restraint of said spring, and means actuated by the rotation of said! drum for de creasing the operative efiect of said jet irnpulses as their rapidity increases.

In a speedometer, the combination of a rotatably mounted speed index drum open at both ends, a control spring therefor, a pulsating air jet nozzle diagonally directed against the surface of an element of said drum to rotate the same, said nozzle being in open comn'iunication with anV air supply source, a lateral opening in the air passage leading to saidv nozzle, and. a valve plate mounted to rotate with said drum t0 vary the arca of said lateral open-ing in proportion to the increase in rapidity 'of the jet impulses from said nozzle.

6. In a speedometer, the combination of a rotatably mounted speed index drinn, a control spring therefor, an air'passap'e leading from a source of air jet propufsion, a nozzle leading from saidv passage and diagonally directedl toward the surface of'said drum, a lateral vent from sai-d passage and a valve disk having an involute periphery, said disk :mounted4 to rotate With said drum and to gradually uncover said vent as the rapidity of the air jet impulses increase.

JAMES T. SIBLEY. 

